We conducted secondary analyses of data from a randomized trial testing the effectiveness of Assertive Community Treatment (ACT) in delivery of integrated dual disorder treatment (IDDT) to explore the impact of IDDT delivered through ACT teams compared with standard clinical case management for dually-disordered persons with and without antisocial personality disorder (ASPD). This analysis included 36 individuals with ASPD and 88 individuals without ASPD. Participants with ASPD assigned to ACT showed a significantly greater reduction in alcohol use and were less likely to go to jail than those in standard clinical case management, whereas participants without ASPD did not differ between the 2 case management approaches. There were no significant differences for other substance use or criminal justice outcomes. This study provides preliminary evidence that persons with co-occurring serious mental illness, substance use disorders, and ASPD may benefit from delivery of IDDT through ACT teams.